[The Panther]

The AI will attack you quite reliably if you have a lot of provinces and a small army. In fact, nearly all AIs will pile on once your army size begins to shrink. Once the ball starts rolling like that against you, it is very hard to recover. If you are on the top of the province graph and near the bottom of the army size graph, you will find yourself in a LOT of wars.

One way to avoid this is to put in 11 PD everywhere. The AI always knows your PD level in every province and will add that to your army size. Since there is no possibility of recruiting armies as fast as the AI does on the impossible level (and to a lesser extent, the hard level), use of PD can give you time to build up SCs, summons, artifacts, build forts, and do all the stuff that happens every game in MP but never in SP by the AI.

Once you get 11 PD everywhere, they will lose a few hawks or wolves to your PD and then quit attacking you. After some indeterminate number of turns with no attacks, they will be at peace with you but never annouce the fact.